Log Message:
py-websockets: updated to 4.0.1

4.0:

Warning: Version 4.0 enables compression with the permessage-deflate extension.
In August 2017, Firefox and Chrome support it, but not Safari and IE.
Compression should improve performance but it increases RAM and CPU use.
If you want to disable compression, add compression=None when calling \ 
:func:`~server.serve()` or :func:`~client.connect()`.

Warning: Version 4.0 removes the ``state_name`` attribute of protocols.
Use protocol.state.name instead of protocol.state_name.

Also:
:class:`~protocol.WebSocketCommonProtocol` instances can be used as asynchronous \ 
iterators on Python ≥ 3.6. They yield incoming messages.
Added :func:`~websockets.server.unix_serve` for listening on Unix sockets.
Added the :attr:`~websockets.server.WebSocketServer.sockets` attribute.
Reorganized and extended documentation.
Aborted connections if they don't close within the configured timeout.
Rewrote connection termination to increase robustness in edge cases.
Stopped leaking pending tasks when :meth:`~asyncio.Task.cancel` is called on a \ 
connection while it's being closed.
Reduced verbosity of "Failing the WebSocket connection" logs.
Allowed extra_headers to override Server and User-Agent headers.